我需要验证字段只包含范围内的数字。所以我试着写一个指令:
@Directive({
selector: "[input-limitation]",
host: {
'(input)': 'onChange($event)',
}
})
export class InputLimitationDirective {
@Input("input-limitation") settings: InputLimitationSettings;
public constructor(private el: ElementRef) {
let self = this;
console.log(":::::::::::::::: el.nativeElement", el.nativeElement);
//jQuery(el.nativeElement).on('keypress', function (e) { self.onChange(e) });
};
private onChange($event) {
console.log("InputLimitationDirective", this.settings);
if (this.settings.InputType = "number") {
return this.numberLimitation($event);
}
}
private numberLimitation($event: any) {
let val: number = $event.target.value;
console.log("InputLimitationDirective", val);
console.log(val, this.settings.MinValue);
console.log(!val, val*1 < this.settings.MinValue*1);
if (!val || val*1 <= this.settings.MinValue*1) {
console.log("1 case");
event.preventDefault();
event.stopPropagation();
return false;
}
else if (val*1 >= this.settings.MaxValue*1) {
console.log("2 case");
event.preventDefault();
event.stopPropagation();
return false;
};
return true;
}
}
以这种方式使用:
<input (change)="totalAmountChanged($event.target.value)"
[(ngModel)]="model.UsedVolume"
[disabled]="!isEditMode"
type="number"
[input-limitation]="usedVolumeInputLimitationsSettings"
pattern="^[1-9]\d*$" min="1" max="999" maxlength="3"
class="form-control length-3-input" />
但这是一个大问题: 1.此限制在Angular 2模型改变后触发,因此我将在模型中获得0值(但我需要1作为最小值)。 2.这只是改变输入值,而不是Angular 2模型值。
那么,在Angular模型改变之前,是否可以验证和阻止某些输入?
答案 0 :(得分:0)
我应该使用自定义值访问器来实现它。这是一个示例:
const CUSTOM_VALUE_ACCESSOR = new Provider(
NG_VALUE_ACCESSOR, {useExisting: forwardRef(() => MaxValueAccessor), multi: true});
@Directive ({
selector: 'input[max]',
host: { '(input)': 'doOnChange($event.target)' },
providers: [ CUSTOM_VALUE_ACCESSOR ]
})
export class MaxValueAccessor extends DefaultValueAccessor {
onChange = (_) => {};
onTouched = () => {};
writeValue(value:any):void {
if (value!=null) {
super.writeValue(value);
}
}
doOnChange(elt) {
var val = elt.value;
// check value here
elt.value = val;
this.onChange(val);
}
}
这样您就可以插入ngModel
处理。
有关详细信息,请参阅此问题: